Monitoring, for the human organism, the potential genetic hazards of the environment is of incalculable value for protecting human health and genetic heritage. Currently, only two higher eukaryotic genetic systems are employed to monitor in situ environmental mutagens in air and in water. Neither of these, however, have the genetic resolution to record frequencies and types of DNA alterations. The objective of this research is to develop a series of waxy pollen mutants in barley which will be highly sensitive to low levels of mutagens in the environment and will identify the type of mutation, i.e., frameshift or base substitution, induced. These mutants will be in a widely adapted plant capable of in situ mutagen monitoring in and around factories, laboratories, an reactors, on farms and in mobile air pollution monitoring laboratories. The waxy pollen system was chosen because it can record mutation events at the waxy locus occurring as low as one in 10 to the minus 6th power pollen grains. Waxy mutant alleles will be induced by basesubstitution (b.s.), frameshift (f.s.), and deletion producing mutagens. They will be selected and mapped from recombination and deletion mapping data. Frequencies of reverse mutations in putative f.s. and b.s. mutants following treatments with a series of b.s. and f.s. mutagens will establish the desired mutagen testers. These testers will be analyzed for mutagen sensitivity and monitoring capability under simulated monitor conditions and in mobile air pollution monitoring laboratories. To confirm the types of mutations involved in the waxy mutants the isolation, purification and sequencing of the protein product UDPG glucosyltransferase will be attempted.